Printed Circuit Design & Fab - July 2008 - (Page 15)

The PCB Surface Finish universe Or, why is immersion silver the preferred finish in ballistic missile nosecones? Our challenge will be in giving adequate coverage to all SurFACe FInISHeS. What more can be the various views on surface finishes. said about circuit board surface finish At MacDermid, I’ve spent the better part of 20 years processes? Perhaps I’m too close to the involved in surface finishes. On the lab bench, I mixed topic, but I’m continuously bombarded the chemicals. At the EMS site, I soldered the test vehiby columns, publications, conferences, cles. In the board shop, I suffered from “nickel itch.” technical reports, press releases, and And back here at my desk, I’ve attempted to coordinate advertising on surface finishes. A porthe data from all of these activities into a message to the tion of these are self-aggrandizing don industry. As I get older, and less able to tend to the lab presentations of semi-scientific technicullEn bench, I’m assisted by lots of more capable people. These cal results. Others may contain nugpeople will be sending in reports on specific surface finish gets of precious information. But in topics as we attempt to tackle them. It’s a big project, so the hallways of the technical conferences and at the bar let’s get started. before the tradeshow, you’ll get the real story on surface Lao Tze gave us the wisdom; “The journey finishes. How that OEM in Germany likes to of a thousand miles begins with just one use this surface finish, while that other step.” Taking that first step into the assembler won’t use such-and-such, Emerging big arena of surface finishes, I ever since they got burned with Finishes plan to divide the topic into that terrible failure mode. And Fully Loaded Environment "bite-sized" units as outlined why is immersion silver the Cost in the central figure. åpreferred finish in ballistic In addition, I hope missile nosecones? I guess you’ll embrace the idea of there is always more to emailing questions that say about surface finFailure Engineering Modes Ease can be handled in the ishes. The proof is in the PCB column. Admit it, we’ve fact that people keep Surface Finishes all complained at how talking about them. information is presented The chatter is not in the media. (Just think all technology. Pricing. Production Regional about politics, nobody Specification. Operator Proven Preferences likes the news coverage of complaints. Document the presidential campaigns.) updates. Phosphorous conInstead of complaining, be part tent. Good service guys. The Functional Electronics of the solution! Bring us ideas Japanese market. Waste water. Capabilities Sector for columns on surface finishing, And …failure modes. Did I forget and we’ll have an honest-to-goodness to mention failure modes? The list debate, here in our own small world of of topics continues to grow, and now PCB manufacturing. On reflection, I guess I do the list will become a! series of columns in understand why the topic of surface finishes is so widely this magazine. Our charter? To discuss all aspects of surinvestigated, and why there are so many articles, conferface finishes, not just the same old boring solderability ences, etc on the topic. There is always change in board comparison charts, but the whole spectrum of hallway finishing technology, and there is always news in the surconversations. In this series of columns we will address face finish front. I congratulate PCD&F for bringing the printed circuit board surface finishes, a.k.a. final finishes spotlight to surface finishes. And I hope you’ll accept the or solderable finishes. We will keep the columns fresh, responsibility for helping shape this column. You can send and the subjects diverse. your questions to the magazine or directly to the columnists You may have noticed that this industry is full of via the email address of the authors. pcd&f technology enthusiasts (geeks). So often, we get all wrapped up in discussions of ohms and thickness distribution and surface analysis equipment. Of course, we don cullEn is the director - oeM and assembly applications for will cover plenty of technical jargon, but we will always MacDermid, Inc. He will be a regularly featured columnist on the give the real-life applications view of the technology. Final Finish Forum. He can be reached at dpcullen@macdermid.com. JULY 2008 printEd circuit dESign & fAB 15

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Printed Circuit Design & Fab - July 2008

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